1. Field of the Invention
This invention relates to a vehicle lamp assembly and, more particularly, to a vehicle lamp assembly having a heat sink with a light shield.
2. Description of the Related Art
In the field of vehicle lighting systems, government regulations require emitted beams to conform to prescribed patterns. For example, a headlamp is required to produce a low and a high beam. High beams cast most of their light straight ahead in order to maximize the distance that a driver can see. However, high beams generally produce too much glare for safe use when other vehicles are present on the road either in front of the vehicle or oncoming toward the vehicle.
Upward projected light can also “back dazzle” a driver when driving in fog, rain and snow due to retro-reflection of the water droplets. FIG. 1 illustrates a portion of a prior art headlamp assembly showing stray light rays emitted from a light-emitting diode (LED). The rays emitted by the light source are not controlled and consequently leave the headlamp uncontrolled. The stray light rays can cause glare and back dazzle.
Low beams, sometimes called dipped beams, have a more controlled beam pattern of upward light and direct most of their light downward and rightward (in right-traffic countries) or leftward (in left-traffic countries) to provide safe forward visibility without excessive glare to oncoming drivers or back dazzle to the driver of the vehicle.
Further, most international regulations specify a beam with a sharp, asymmetric cut-off that prevents significant amounts of light from being cast into the eyes of the drivers of preceding or oncoming cars.
In some applications, a moveable shield, shade or mask is located between a reflector and a lens in the headlamp assembly. The projection of the top edge of the shield provides a beam cut-off that assists in shaping the beam pattern in order to comply with regulations. The shield, shade or mask is oftentimes a separate part in the headlamp assembly and in some applications, requires a separate driver, such as a solenoid, to actuate the shield, shade or mask between inactive and active positions.
What is needed, therefore, is an improved system and method for shielding a beam pattern in order to shield direct light from a light source, such as a light-emitting diode (LED), in order to reduce or eliminate glare and back dazzle.